Effects of smectite, salinity and water content on sedimentation and self-weight consolidation of thoroughly disturbed soft marine clay

Addition of a high-swelling smectite to low-activity-mineral-dominated Leda clay influenced the settling mode, settling/consolidation rates and the final sediment water contents attained when suspensions ranging in water content from 500 to 6000% were allowed to settle under salinity conditions ranging from 30 to 0.5 g/l, and to undergo self-weight consolidation for 14 days. The presence of high-swelling smectite extended the salinity and water content ranges over which consolidation settling and zone settling occurred and the final water content for any initial-water-content/salinity condition increased as the amount of high-swelling smectite increased. The settling and consolidation rate patterns change with time in a manner that is dependent on all of settling mode, water content and salinity. At high-swelling smectite content <5%, the lowest sediment water content is attained under brackish (8–2 g/l salinity) conditions with initial suspension water contents below 1000%. For contents >10%, the lowest sediment water content is attained at high salinity and the lowest possible initial suspension water content.